@GL: What current do you get if you give the mosfet slightly under 5 volts at the gate?

Look at the scopeshot (blowup attached below)  that gave her what we calculate as the 320 mA. The gate is only getting about 5 volts at most.

Quote from: TinselKoala on May 11, 2012, 04:07:36 AM
@GL: What current do you get if you give the mosfet slightly under 5 volts at the gate?

Look at the scopeshot (blowup attached below)  that gave her what we calculate as the 320 mA. The gate is only getting about 5 volts at most.

TK,

I get 1.07 Ampere through the circuit when using 5 volt at the MOSFET gate.
I had to adjust the gate voltage down to 4.14 Volt to get 0.32 Ampere through the circuit.

GL.

Quote from: Groundloop on May 11, 2012, 04:21:00 AM
TK,

I get 1.07 Ampere through the circuit when using 5 volt at the MOSFET gate.
I had to adjust the gate voltage down to 4.14 Volt to get 0.32 Ampere through the circuit.

GL.

Thank you for checking. 

So a mosfet getting 12 volts to the gate should pass a lot of current, several amps at least, easily visible on a CVR trace, as your experiment has shown, right?

And if it gets only 5 volts the current drops considerably, and if it got only 4 volts the current would be even less than 320 mA.

That sounds to me like a mosfet might make a pretty good amplifier if it is operated in this rather linear response mode !

All of my measurements on that scope trace are as accurate as I could get; I blew up the image and used calipers to make the measurements, but because of the fuzz it is difficult to decide where to put the line.  So I tried to put it in the middle of the fuzz. But without knowing the fine details of the fuzz, it's not possible to know the precise voltage level that the mosfet got. Perhaps it was seeing less than 5 full volts. It would be nice to know, from Ainslie, just exactly what that voltage was. Too bad the scope wasn't set to display it, as it easily could have been.

I think that the mosfet was just underdriven for that shot and that the 320 mA figure might be close to the true DC current during those 16 millisecond ON periods. Ainslie's load is also given as 11.11 Ohms.

Have you had any luck reproducing this other shot... the one where +12 volts is definitely applied to the gate -- or somewhere -- for 16 full seconds each period ... but there is NO current flow whatever? This is Figure 3 from the first paper.

Here's a neat little picture I found. 

I sure would have liked to have seen the event that produced this effect. I've seen it before, and I think I know why it happened in this particular case. But I wasn't there, and the person who was there has not described what happened in much detail, other than to state

Quotegolly guys.  I've just had the batteries catch fire.  Connecting leads vaporised.  How's that for proof of energy.  I was careless with one of those connections - I think.  Not actually sure what happened.  I'll test their voltage again when I've settled my nerves a bit. 
Good heavens.  I've heard about this happening.  Never actually seen it.

I may be more actually sure what happened, even though I wasn't there. But certainly now... it seems that to describe this event as "two batteries catching fire" without giving more details.... is rather misleading.  They didn't "catch on fire"... they very nearly blew up due to being short-circuited by mishandling, and the only thing that prevented it was the fusing of the connecting wire and the clips. Had that been a heavy-gauge wire, the batteries could well have exploded before the short circuit was broken.

I really hope that people playing around with big lead acid batteries, large capacitances, high voltages, and strong magnets are fully aware of the very real hazards these things can present. Has a lesson been learned? Do we see fuses or circuit breakers anywhere, in further work from this group?

Nice clips, though. Regulation battery clips, just like those on my automatic battery charger.

Quote from: Rosemary Ainslie on May 10, 2012, 10:54:11 PM
And then onto this last scheduled point... NUMBER 4

In answer to 'when does the DC become DC'?  It is DC when it is continually greater than ground for the duration of a switched cycle.  There is no other time.

But what about long duty cycles? Say you had a two minute period of positive signal and a sixteen second period of ground signal during each period coming from a FG. Would it be fair to say that, during a one minute interval in the middle of the two minutes ON time.... the signal is DC? Why not? How would an observer tell the difference between that two minutes ON signal and a strictly inarguably DC wires-from-battery type of permanently ON signal?

Quote
And regarding your 'edit' - our 50 second timebase setting does NOT have a blown MOSFET.  Never has and NEVER did.  This is a gross misrepresentation of the fact is thereby also SLANDEROUS.  Again.  Why is it that Harti is encouraging this editorial bias - and, for this matter, this SLANDER.  This ALLEGATION that our MOSFET has blown is EASILY DISPROVED.  And we shall do so in our demonstrations.  At which point TK will be obliged to retract this statement.  It is a shame that he's not obliged to do so BEFORE our demonstration.  But just as a point of interest.  TK CLAIMS to be credentialed.  He is, thereby CLAIMING a level of professionalism.  That professionalism includes a PLEDGE to act in a professional manner. A professional manner precludes any criminal or nefarious activitiy.  Slander is a criminal offense.  Thereby does TK disprove his own claims of professionalism.  And with it he disproves his CLAIMED accreditation.

Regards,
Rosemary

Oh... really? NEVER did? Well, I don't know what TIMEBASE setting you used to blow the two mosfets you blew last year in March ... but certainly you have blown mosfets in the past, so why is it not possible that you have done so again? I mean... it's pretty clear that you don't know how to identify a blown mosfet. Or how to explain that scope trace.
(I manage to damage mosfets frequently; it's easy to do, even by such innocent things as soldering to their pins or a static discharge from shuffling your feet on the carpet. But that's just me.... you are much more careful, I'm sure.)

QuoteJust had a diagnosis.  2 of the MOSFETs blown.  Interestingly it's enough to block that oscillation.  Seems that they all need to work but still not sure if all 5 are required.  I'll let you know.  They're to be replaced - hopefully - by Monday.   Â« Last Edit: March 31, 2011, 03:21:14 PM by Rosemary Ainslie »   

Emphasis in the original:
http://www.overunity.com/10407/rosemary-ainslie-circuit-demonstration-on-saturday-march-12th-2011/msg279934/#msg279934

Too bad we don't know which mosfets blew or how they faulted.